1. Field of the Invention
The present invention relates to compounds containing meta-biphenylenedioxy moieties. It relates particularly to diamines and dianhydrides which contain meta-biphenylenedioxy moieties.
2. Description of the Related Art
The need exists for high temperature polymers which can be processed into pads for aircraft and spacecraft and can withstand both highly oxidative and intense radiation environments. To be useful in the aerospace industry, polymers must be processable via thermoplastic means. This allows them to be formed or shaped into complex pads which may or may not contain reinforcements such as glass or graphite fibers.
Bell (U.S. Pat. No. 4,094,862) developed a method to prepare insoluble thermoplastic aromatic polyimides which have uniquely low softening temperatures. This method involved the reaction of an aromatic dianhydride with a meta-substituted aromatic diamine in a suitable solvent. The polymers formed from the meta-substituted diamines had glass transition (Tg) temperatures which were 50.degree.-70.degree. C. lower than their para-counterparts.